Business Segments (Details) (USD $)	3 Months Ended		6 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012
Segment Reporting Information [Line Items]
Revenues From External Customers	$ 399,411,000	$ 308,432,000	$ 915,286,000	$ 780,272,000
Margin	183,856,000	171,951,000	415,480,000	392,187,000
Operations And Maintenance Expenses	65,103,000	60,532,000	121,039,000	118,952,000
Income From Equity Method Investments	12,437,000	11,652,000	19,592,000	17,944,000
Operating Income (Loss) Before Income Taxes	82,814,000	76,846,000	222,191,000	203,780,000
Income Before Income Taxes	92,045,000	82,816,000	233,941,000	208,582,000
Number Of Operating Segments	2
Regulated Operation [Member]
Segment Reporting Information [Line Items]
Revenues From External Customers	399,411,000	308,432,000	915,286,000	780,272,000
Margin	183,856,000	171,951,000	415,480,000	392,187,000
Operations And Maintenance Expenses	65,037,000	60,511,000	120,919,000	118,908,000
Income From Equity Method Investments	0	0	0	0
Operating Income (Loss) Before Income Taxes	82,884,000	76,872,000	222,396,000	203,912,000
Income Before Income Taxes	79,678,000	71,189,000	214,555,000	190,770,000
Non Utility Activities [Member]
Segment Reporting Information [Line Items]
Revenues From External Customers	0	0	0	0
Margin	0	0	0	0
Operations And Maintenance Expenses	66,000	21,000	120,000	44,000
Income From Equity Method Investments	12,437,000	11,652,000	19,592,000	17,944,000
Operating Income (Loss) Before Income Taxes	(70,000)	(26,000)	(205,000)	(132,000)
Income Before Income Taxes	$ 12,367,000	$ 11,627,000	$ 19,386,000	$ 17,812,000